If there are $$n$$ capacitors in parallel connected to $$V$$ volt source, then the energy stored is equal to

A charged particle $$q$$ is placed at the centre $$O$$ of cube of length $$L(ABCDEFGH).$$ Another same charge $$q$$ is placed at a distance $$L$$ from $$O$$. Then the electric flux through $$ABCD$$ is

If a charge $$q$$ is placed at the center of the line joining two equal charges $$Q$$ such that the system is in equilibrium then the value of $$q$$ is

If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a